'The UK has let it be known that this will not be a pledging summit. But that does not mean it cannot help the villagers of Engare Sero, the slum girls of Kibera (pictured) and millions like them.' Photograph: David Levene for the Guardian

It seems a long time since G8 leaders last gathered in the UK for their annual get-together. Back in 2005, we were at the height of a global boom and there was a real sense that this could be the summit to Make Poverty History.

I was proud to be a small part of the campaign that urged world leaders to boost aid, cancel debt and "make trade fair". We only got two out of three: debt and aid, and aid was not fully delivered. Yet despite that relative failure, the wins we did get made a massive difference to millions of the world's poorest people. To take just one example, 30% fewer children die of malaria in Africa than did in 2004 – that's 300,000 lives saved every year.

The week before the G8 convenes once again is a natural time to reminisce about the good old days but this is about more than nostalgia. Even in today's age of austerity, the G8 has a chance to build on the successes of the Gleneagles summit and, in particular, tackle the forgotten scandal of hunger.

A child dies every 10 seconds from malnutrition – not because their parents are reckless, stupid or lazy – but because they were unlucky enough to be born at a time and place where there is too little food available or, perhaps more tragically, where people cannot afford to buy the food that is.

One in eight people in the world will go to bed hungry tonight. That's 870 million people. The total population of the G8 is just 890 million. Just imagine the urgency to act if those 870 million lived in the G8 rather than in Africa, South Asia and other poor countries.

Since 2005, I've visited developing countries and campaigned with Oxfam at a number of G8 and G20 summits – pushing leaders to deliver on their promises to the poorest and seeing for myself the difference the money can make. In Tanzania, I met the charming and humbling villagers of Engare Sero, who explained to me that for them aid meant a grain bank so they no longer had to endure a life-sapping 10-day round trip for a single bag of maize. In Nairobi's Kibera slum I met girls as young as eight scavenging for food who were forced to give sexual favours to the criminals who controlled the dump so they could get to the fresher garbage as it was unloaded from the lorries.

At Tokyo and then Toronto leaders pledged again to deliver the aid they had promised, but with the notable exception of the UK, those expected to stump up significant sums have fallen short – increases, yes but billions shy of their promises.

In Cannes at the G20, we hoped a Robin Hood tax on banks might fill the gap – it still might. Eleven countries in Europe are pressing ahead with a financial transaction tax that could raise tens of billions from the sector that caused the economic crisis to help people in Europe and poor countries. The UK is not only not one of those countries, but George Osborne is going to court to block it.

This year's G8 is unlikely to see much movement on aid beyond the very welcome additional money for nutrition announced at last weekend's hunger summit. The UK has let it be known that this will not be a pledging summit. But that does not mean it cannot help the villagers of Engare Sero, the slum girls of Kibera and millions like them.

Protecting poor people from land grabs, making it easier for them to find out what companies and their governments are doing and stopping the ridiculous situation where G8 members' policies actively encourage land to be used for growing fuel rather than food: all these will help.

It is money that could be invested in farms – providing the seeds, equipment and knowhow to get more food from the same plot of land. And it could be used to provide safety nets to help people whose ability to earn a living has failed to keep pace with rising food prices.

In the 6th century BC the Chinese philosopher Lao Tsu observed: "The people are hungry: it is because those in authority eat up too much in taxes." Now in large parts of the world the reverse is true.

The actions the G8 needs to take are relatively simple. They need to agree new global rules – on information exchange and public information so it is clear who assets belong to – to ensure that companies can no longer use tax havens to avoid paying their fair share here and in poor countries. Here David Cameron has a crucial role to play – the UK is responsible for more tax havens than any other country in the world.

As the prime minister said earlier this year: "The fact is the poorer the nation the more they need the tax revenues but often the weaker the capacity they have to collect them. All of this in developed and developing countries alike comes down to a simple issue of fairness." I couldn't have put it better myself.